Mucinous cystic neoplasm mimicking pancreatic pseudocyst and progressing to adenocarcinoma: A case report

Abstract

BACKGROUND

As a heterogeneous group of lesions, pancreatic cystic lesions (PCLs) vary enormously in malignant potential, mandating different treatment strategies. Despite significant advances in diagnostic imaging and laboratory tests, the accurate diagnosis of PCLs remains challenging, leading to overtreatment or delayed/missed surgical timing in patients with PCLs.

CASE SUMMARY

We present a case of a 64-year-old female patient in whom an asymptomatic, incidental cystic mass was found in the pancreatic tail on a routine abdominal ultrasound. After a comprehensive work-up with laboratory examinations, contrast-enhanced computed tomography, magnetic resonance imaging, and magnetic resonance cholangiopancreatography, a pancreatic pseudocyst was suspected. Subsequent endoscopic ultrasound with fine-needle aspiration and needle-based confocal laser endomicroscopy supported a benign diagnosis. Follow-up computed tomography and magnetic resonance imaging examinations five months later showed significant cyst shrinkage without any abnormalities. However, three years after being lost to follow-up, the patient was readmitted and diagnosed with pancreatic adenocarcinoma with multiple metastases, suggesting that the initial lesion was a mucinous cystic neoplasm misdiagnosed as a pancreatic pseudocyst.

CONCLUSION

Comprehensive integration of all available information (e.g., cyst features, abnormal imaging findings, cyst biochemistry, clinical history, and patient demographics) rather than over-reliance on imaging or endoscopic findings is pivotal to diagnosing PCLs, and patients with concerning features should undergo strict surveillance.

Keywords: Pancreatic cystic lesion; Pancreatic pseudocyst; Pancreatic cystic neoplasm; Diagnosis; Endoscopic ultrasound; Imaging; Case report

Core Tip: Advances in imaging are resulting in more incidental diagnoses of pancreatic cystic lesions. However, they can be challenging to subclassify, and their malignant potential varies, requiring different treatment approaches. Endoscopic ultrasound and ancillary methods like fine-needle aspiration and needle-based confocal laser endomicroscopy are significantly improving the sensitivity and accuracy of diagnosis. However, in this case, all these methods failed to identify subsequent malignant transformation, emphasizing the importance of attention to detail and strict and close surveillance where clinical uncertainty exists.